<template>
  <div class="pagination">
    <button :disabled="pageNo==1" @click="$emit('getPage',pageNo-1)" >上一页</button>
    <button v-if="startNumAndEndNum.start > 1" @click="$emit('getPage',1)">1</button>
    <button v-if="startNumAndEndNum.start > 2">···</button>
    <button v-for="(page,index) in startNumAndEndNum.end" 
    :key="index" v-if="page >= startNumAndEndNum.start" 
    @click="$emit('getPage',page)" 
    :class="{active:pageNo == page}">{{page}}</button>
    <button v-if="startNumAndEndNum.end < totalPage - 1">···</button>
    <button v-if="startNumAndEndNum.end < totalPage" @click="$emit('getPage',totalPage)" :class="{active:pageNo == totalPage}">{{totalPage}}</button>
    <button :disabled="pageNo == totalPage" @click="$emit('getPage',pageNo+1)">下一页</button>
    <button style="margin-left: 20px" >共 {{total}} 条</button>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  props: ["pageNo", "pageSize", "total", "continues"],
  data() {
    return {};
  },
  computed: {
    totalPage() {
      return Math.ceil(this.total / this.pageSize);
    },
    startNumAndEndNum() {
      const { pageNo, continues, totalPage } = this;
      let start = 0,end = 0;
      //总页数不足，显示不了连续页码效果的处理代码
      if (totalPage < continues) {
        start = 1;
        end = totalPage;
      } else {
        start = pageNo - parseInt(continues / 2);
        end = pageNo + parseInt(continues / 2);
        //纠正起始页为负数情况
        if (start < 1) {
          start = 1;
          end = continues;
        }
        //纠正结尾页超出边界
        if (end > totalPage) {
          start = totalPage - continues + 1;
          end = totalPage;
        }
      }
      return { start, end };
    },
  },
};
</script>

<style lang="less" scoped>
.pagination {
  text-align: center;
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>